Gallery @museum.de

M: That's just a stunning view of the Open Air Museum's grounds and the lake!

F: But don't just let your eye rove into the distance. If you turn around, you'll be able to see the wooden octagon of our mill up close. The octagonal masonry ends about two metres or six and a half feet above the gallery. Above that level, you're looking at the smock, a timber structure that's about 10 metres or 32 feet tall, made of oak and pitch pine. And that is topped by the rotating cap with the sails.

M: The gallery surrounding the timber octagon is similarly eight-sided. There are two doors leading out on to the gallery on opposite sides. If you're afraid of heights, you probably shouldn't look down between the floorboards. Perhaps better concentrate on the railing. Can you imagine why it's not vertical, but leans slightly outwards?

F: The answer is strictly technical in nature and has to do with the rotation of the sails. The length of the sails has been calculated to take maximum advantage of the space available, leaving just seven centimetres – a couple of inches – of leeway at the lowest point as they whizz past the gallery floor. If the railing were vertical, the sails would need to be much shorter so as not to catch as they rotate. So the railing dodges the circular motion by, as it were, leaning back a little to let the sails whoosh by.

M: But the sweep mustn't turn too quickly, either! The maximum is 20 revolutions a minute, otherwise the cap, which sits loose on the tower, would lift off and get tangled.

F: During gales and thunderstorms, or even just at the end of the working day, the miller would come out on to the gallery and activate a brake to stop the wind shaft moving. The mobile cap would carry on turning, ensuring that that the wind can't rip off the sails. But the large frame with the sails would stand still.

M: Whether the sails form an upright cross or an X, whether the bottom wing is on the right or left-hand edge of the gallery – all that was a form of communication! When you go back downstairs after your tour, you'll find a brief introduction to the language of mill sails to the left of the exit.